Thermionic valve



July 16, 1929. c. SFRANKLIN THERMIONIG VALVE Filed June 11, 1924 Eig. Z

. CHARLES s. FRANKLIN INVENTOR ORNEY i so Patented July 16, 1929.

UNITED STATESy PATENT ,()FlilCl CHARLES SAMUEL FRANKLIN, 0F SAINT MICHAELS, ENGLAND, ASSIGNOR TO RADIO CORPORATION 0F AMERICA, A CORPORATICN OF DELAWARE.

mnemonic var .vn

i i Application. filed June 11, 19,24, Serial No. 719,253, and in Great Britain .Tune 20, 1923.

This invention relates to triode valves and its object is to produce a valve capable of pro- `ducing high frequency oscillations of considerable power.

In a valve as usually constructed the connections to the grid and to the cathode are brought out through the samev end of the valve and in consequence there is a very intense and concentrated high tension high frequency field acting on the glass which supports the grid and cathode. This results in a limitation of the voltage and therefore of the power at which the valve can be worked since the glass around the grid and cathode seals or supports quickly gets heated vand may even be melted so that the valve is destroyed.

As a result of numerous experiments I have discovered that by arranging the seals and supports of the grid at one end of the valve and those of the cathode at the other end of the valve I can avoid this concentrated field and its effects.

According to this invention therefore I construct a valve in which the grid is supported from one end of the valve through which its connection is sealed and the cathode is supported at the other end of the valve through which its connections are sealed. The invention is particularly applicable inthe case of valves in which the envelope is mainly formed of metal which functions as the anode. In

- such a case I weld toeach endvof the metal cylinder which forms the anode a glass cylinder or bulb and I support the cathode from one of these bulbs through which I seal the connections and I support the grid from the other bulb and seal its connection therein. In the case of a valve having a glass envelope I support and seal the grid and cathode at oppositevends and I support the anode and arrange the anodeN supports and seal approXimately midway' between the two ends.

My invention isillustrated by the accompanying drawing, in which Figs. 1 and 2 are longitudinal cross sections through valves constructed in accordance therewith.

A is a metal cylinder which acts as the anode. B is a glass cylinder which is sealed to one end of A and to which is sealed a metal plate or cap C. The other end of A is sealed to a glass cylinder orhulb D. The grid G is supported by stout rods E carried by the plate or cap C, while the cathode 'F is sealed into the bulb D.

stancy of waveen'gths.

Such a ,valveis much vmore reliable' than a valve made wlth the grid and cathode brought out at the same end,yand can be worked tohigher voltages.A The heating of the glass dueto hlgh frequency `fields is reduced to a mimmum. Y;

Having descrlbed 4my invention what I claim 1s:-

1,1, A 'vacuum tube device comprising a tubular metal anode, a vitreous closure sealed to one end thereof and having a re-entrant portion, a cathode member positioned within said tubular anode and having supporting members sealed through said 11e-entrant portion, a second vitreous portion sealed tothe other end of said tubular anode, a metal closure therefor, sealed thereto, and a grid electrode member attached to said second metallic closure member.

2. VA vacuum tube device comprising a tubular metal anode, a vitreous closure sealed to one end thereof and having a reentrant portion, supporting means sealed in said reentrode supported by said vitreous closure, a'

metallic closure for the other end of said tubular metal portion, an electrode carried by Said metallic closure, and a vitreous member between said tubular metal portion and said metal closure.

4. A vacuumtube device having an envelope comprising a tubular metal cylinder, a vitreous closure having a reentrant portion for one end of lsaid cylinder, a metal cap for the other end of said cylinder and a tubular vitreous insulating member between said tubular metal cylinder and said metal cap, \tioned vyithin said tubular anode and havnv L said tubular vitreous member being hermetisupporting means extending throu h said cally sealed at op osite ends to said tubular end, a second vitreous portion seule to the l0V metal cylinder an the edge of the metal cap. other end of ,sold tubular anode, a metal K 5 5. A vacuum tube device comprising a closure therefor, qnd another electrode memtubular metal anode, a. vitreous closure sealed ber attached to said metallic` closure member. to one end thereof, an electrode member posi- CHARLES SAMUEL FRANKLIN. 

